Intuitive Surgical, Inc. (NASDAQ: ISRG) has lost nearly $50 per share, or 8%, since short selling website Citron Research targeted the maker of robotic surgical devices on Wednesday. Notably, the company and Wall Street analysts have been very quiet despite the dramatic drop.

Certainly they don't agree with claims from Citron's that it uses fear tactics to sell the device, that there is lack of real scientific evidence that the da Vinci is of any clinical value, or that the botching of "routine" surgeries will cause a world of hurt from lawyers. However, the silence is deafening.

Does this lack of defense indicate that they maybe believe the stock is a little frothy? Or is the silence simply a pooh-poohing of Citron and it research - 'critics are a dime a dozen, we've had them every step of the way building a $20 billion enterprise - they're always wrong,' they might be saying in the boardroom.

Either way, after falling 5.7 percent Wednesday, and trading down another 2.9 percent today investors are getting antsy for some help.